Housing for a radical compressor

ABSTRACT

A housing for a radial compressor is comprised of at least two housing parts manufactured of plastic material for receiving a compressor wheel and for forming a spiral-shaped compressor passage, wherein into the housing between compressor wheel receptacle and compressor passage an annular space is introduced that annularly surrounds the compressor wheel and into which a stabilization element is introduced.

This is a cip application of pending international patent applicationPCT/EP2008/063146 filed Oct. 1, 2008 and claiming the priority of Germanpatent application 10 2007 055 615.4 filed Nov. 20, 2007.

TECHNICAL FIELD

The invention concerns a housing for a radial compressor comprising twohousing parts consisting of plastic and having a spiral-shapedcompressor passage and a compressor wheel disposed in the housing.

PRIOR ART

In DE 103 14 209 B3 a radial compressor as a component of an exhaust gasturbocharger is described that is comprised of two shell-shaped housingparts that are injection-molded from thermoset material. This materialhas a high density so that, in comparison to other conventional chargerhousings of metal, no weight-related advantage results. DE 103 14 209 B3attempts to counteract this in that into one of the housing partschamber-like recesses are introduced that are separated from one anotherby partitions and that essentially extend concentrically to an airintake axis.

The housing parts are glued together which however requires a relativelyhigh manufacturing expenditure. Thermoset resin as a material isfurthermore characterized by a relatively high brittleness and highwater absorption as well as a relatively minimal dimensional stabilityat high temperatures. Moreover, there is great acoustic radiation andthe manufacturing costs are also relatively expensive.

In case of radial compressors moreover a satisfactory operating safetymust be taken into consideration. Because of the high wheel speeds ofturbochargers there is the risk that upon damage of the compressor wheelmetal fragments of the wheel will penetrate the housing of thecompressor and will damage components in the engine compartment of theinternal combustion engine.

SUMMARY OF THE INVENTION

The invention has the object to produce a lightweight dimensionallyprecise housing for a radial compressor with satisfactory seal-tightnessand high heat resistance from plastic material wherein, in case ofdamage of the compressor wheel, the risk of metal fragments flying aboutis to be reduced.

This object is solved according to the invention in that an annularhollow space is provided in the housing which extends around thecompressor wheel and at least one stabilizing element is disposed in theannular space.

The housing according to the invention for a radial compressor iscomprised of at least two housing parts manufactured of plastic materialwhich, on the one hand, are designed for receiving a compressor wheeland between which, on the other hand, a spiral-shaped compressor passageis formed. Into the housing between a compressor receptacle that servesfor receiving and supporting the compressor wheel and the spiral-shapedcompressor passage a circumferentially extending annular space is formedthat annularly surrounds the compressor wheel. In this annular space atleast one stabilization element is introduced.

The housing parts manufactured of plastic material, comprised inparticular of thermoplastic material and produced by theinjection-molding process, for example, of polyphenylene sulfide (PPS),fulfill together with the annular space in which at least onestabilization element is introduced also high safety requirements, inparticular in case of fracture of the compressor wheel. The annularspace is located at the radial outer side of the compressor wheel sothat broken-off wheel fragments that are thrown off tangentiallyoutwardly as a result of the high rotary speed of the compressor wheelwill impact on the annular space and the stabilizing element arrangedtherein. The walls of the annular space ensure already an effectivereduction of the broken-off tangentially thrown wheel parts; inaddition, there is the stabilizing element that is received in theannular space that, on the one hand, counteracts deformation of thewalls of the annular space and improves as a whole the stability of thehousing and, on the other hand, upon impact of a broken-off wheelfragment, provides effective damping. The stabilization elementtherefore has a double function: on the one hand, the annular space andthus the entire housing is supported or reinforced; on the other hand,in case of an accident, the protection from thrown-off wheel fragmentsis improved.

In axial direction the annular space advantageously extends at leastabout the axis length of the compressor wheel wherein optionally also anextension substantially about the length of one of the housing partsthat delimits the annular space may be considered.

As a stabilization element a separate component is to be considered thatis inserted into the annular space. For example, the stabilizationelement is embodied as a fill hose, for example, comprised of aramidefiber or the like, that is inserted into the annular space upon assemblyof the housing. For the purpose of facilitating assembly of the housing,an annular groove can be introduced into one of components delimitingthe annular space and forms part of the annular space and provides areceptacle for the stabilization element already before assembly of thetwo housing parts.

In the radial direction, the annular space has an extension that enablesinsertion of the stabilization element. Relative to the wall thicknessof the delimiting wall the radial extension is preferably a multiple ofthe wall thickness, for example, three times to five times the wallthickness. Moreover, it may be expedient to match the radial extensionof the annular space, viewed about the circumference, to the shape ofthe spiral-shaped compressor passage. Since the compressor passage inthe circumferential direction has a variable diameter, a greater radialextension for the annular space is available in sections of smallerdiameter of the compressor passage than in sections with greaterdiameter.

The manufacture of the compressor housing of thermoplastic material, inparticular PPS, has the advantage of easy manufacture as well as goodrecyclability. In the manufacture by injection molding, a lost coretechnology is not required; manufacture is realized by injection moldingby means of molds of a simple configuration that can be opened andclosed. A further advantage resides in the manufacture of complexgeometries of the housing, for example, a spiral passage with severalundercuts. Finally, thermoplastic materials can be produced with highdimensional precision so that post-processing can be dispensed with orthe need for it is limited. Moreover, the thermoplastic material isheat-resistant, pressure-tight and has excellent sound-insulatingproperties at minimal weight.

A further advantage resides in the possibility of configuring housingparts with constant wall thickness so that material accumulations areavoided and the risk of cavity formation is reduced.

The housing parts can be welded together in particular by way ofultrasonic welding. In order to be able to position the ultrasonic probe(sonotrode) in a simple way at the required welding seam, advantageouslythe contact area between the housing parts to be welded is adjacent tothe axial end face of the housing, in particular adjacent to the intakeside. Moreover, the contact areas between the housing parts arepreferably located at a spacing to the spiral-shaped compressor passage;they are thus removed from the critical spiral area so that the airguiding action on the inner side of the spiral is not impaired by anundesirable burr caused by welding in the wall.

According to a further advantageous embodiment, the housing as a wholeis comprised of three housing parts including a compressor front part, acompressor rear wall, and an inwardly positioned bearing shell. Thecompressor front part and compressor rear wall form the outer housingparts between which the bearing shell is positioned that serves forreceiving the compressor wheel. The annular space is provided preferablybetween the bearing shell and the compressor front part.

Further advantages and expedient embodiments are disclosed in thefurther claims, the figure descriptions, and the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The only FIGURE shows a section of a housing for a radial compressorcomprised of three individual housing parts of thermoplastic materialthat are welded together by ultrasonic welding wherein between aninwardly positioned bearing shell and a compressor front part an annularspace is formed that surrounds the compressor wheel receptacle.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The illustrated housing 1 for a radial compressor is a component of anexhaust gas turbocharger of an internal combustion engine in which theexhaust gases of an internal combustion engine drive a turbine wheelthat is fixedly connected to compressor wheel that is rotatablysupported in the housing 1. By rotation of the compressor wheelcombustion air is sucked into the intake manifold and compressed to anincreased charge pressure at which the combustion air is supplied to thecylinders of the internal combustion engine.

The housing 1 is of a three-part configuration and comprises acompressor rear wall 2, a compressor front part 3, and an inwardlypositioned bearing shell 4 that delimits a compressor wheel receptacle 5for receiving and supporting the compressor wheel that in the embodimentis referenced by reference numeral 7 and is illustrated onlyschematically by a dotted line. The combustion air is axially suppliedto the compressor wheel 7 by an intake socket 6 that is formed in thecompressor front part 3. The compressed combustion air is guidedradially through diffuser 9 into a spiral-shaped compressor passage 8that is delimited by the compressor front part 3 and compressor rearwall 2 and that opens into an outlet socket by means of which thecompressed combustion air is supplied finally to the cylinders of theinternal combustion engine.

Between the compressor front part 3 and the bearing shell 4 acircumferentially extending annular space 10 is formed that radiallysurrounds the compressor wheel receptacle 5 and is separatedfluid-tightly from the compressor wheel receptacle 5 by means of thewall of the bearing shell 4. The annular space 10 has substantially thesame axial extension as the bearing shell 4 and thus also the compressorwheel receptacle 5. A separate component in the form of a fill hose 11is inserted into the annular space 10 that has the function of astabilization element and, in addition to providing reinforcement of thehousing 1, also takes on a safety function in case of an accident inthat broken-off wheel fragments of the compressor wheel 7 that aretangentially thrown outwardly are caught by the stabilization element11.

The housing parts 2, 3, 4 are comprised of thermoplastic material andare joined by way of ultrasonic welding. This is done such that asonotrode is placed onto the contact areas 14, between the compressorrear wall 2, and the compressor front part 3, or 15, between the bearingshell 4 and the compressor front part 3, in order to perform the processof ultrasonic welding. The first contact area 14 between compressor rearwall 2 and compressor front part 3 is located in the radial outer area,neighboring the end face that forms the intake side of the housing. Thecontact area 15, on the other hand, is positioned radially inwardlydisplaced between the bearing shell 4 and the compressor front part 3immediately neighboring the compressor wheel receptacle 5 but also onthe side of the housing that is facing the intake side.

The bearing shell 4 is formed in such a way that in the area of theannular space 10 in the bearing shell 4 an annular groove 16 is formedthat is supplemented to the annular space 10 by the compressor frontpart 3 to be positioned thereon. The annular groove 16 has the advantagethat already before positioning the compressor front part 3 a receptaclefor insertion of the stabilization element is provided; this is inparticular advantageous in the variant embodied as a separate componentin accordance with FIG. 1 because in this case the stabilization elementembodied as a separate component is received safely in the annulargroove 16 before positioning the compressor front part.

1. A housing for a radial compressor, comprised of at least two housingparts (2, 3, 4) manufactured of plastic material for receiving acompressor wheel (7) and for forming a spiral-shaped compressor passage(8), wherein in the housing (1) between a compressor wheel receptacle(5) and the spiral-shaped compressor passage (8) a hollow space isintroduced, the hollow space being an annular space (10) that surroundsthe compressor wheel (7) with at least one stabilization elementdisposed in the annular space (10).
 2. The housing according to claim 1,wherein the annular space (10) is delimited by two housing parts (3, 4).3. The housing according to claim 2, wherein the housing parts thatdelimit the annular space (10) are embodied as inwardly positionedbearing shell (4) forming the compressor wheel receptacle (5) and ascompressor front part (3).
 4. The housing according to claim 3, whereinthe bearing shell (4), on the side facing away from the compressor wheelreceptacle (5), forms an annular groove (16) that forms a part of theannular space (10).
 5. The housing according to claim 1, wherein thehousing is of a three-part configuration and comprises the compressorfront part (3), a compressor rear wall (2), and the inwardly positionedbearing shell (4).
 6. The housing according to claim 5, wherein thecompressor front part (3) has a contact area (15) with the bearing shell(4) and a further contact area (14) with the compressor rear wall (2).7. The housing according to claim 1, wherein the contact areas (14, 15)between the housing parts (2, 3, 4) are arranged at a spacing to thespiral-shaped compressor passage (8).
 8. The housing according to claim7, wherein the contact areas (14, 15) are positioned adjacent to theintake opening (6) of the housing (1).
 9. The housing according to claim1, wherein the housing parts (2, 3, 4) are welded to one another, inparticular by ultrasonic welding.
 10. The housing according to claim 1,wherein a stabilization element in the annular space (10) is embodied asfill material.
 11. The housing according to claim 10, wherein the fillmaterial is comprised of plastic material.
 12. The housing according toclaim 1, wherein the stabilization element in the annular space (10) isembodied as a separate component, for example, as a fill hose (11). 13.The housing according to claim 1, wherein the housing parts (2, 3, 4)are manufactured of thermoplastic material and in particular producibleby injection molding.
 14. The housing according to claim 13, wherein thehousing parts are comprised of polyphenylene sulfide (PPS).